Rice Cultivar Designated &#39;CL261&#39;

ABSTRACT

Hybrids and derived cultivars of the rice cultivar designated ‘CL261’ are disclosed. The invention relates to hybrid rice seeds and plants produced by crossing the cultivar ‘CL261’ with another rice cultivar. The invention further relates to other derivatives of the rice cultivar ‘CL261.’

The benefit of the 4 Oct. 2010 filing date of international applicationPCT/US2010/051247, and of the 8 Oct. 2009 filing date of U.S.provisional patent application Ser. No. 61/249,641 are claimed under 35U.S.C. §119(e) in the United States, and are claimed under applicabletreaties and conventions in all countries.

TECHNICAL FIELD

This invention pertains to the rice cultivar designated ‘CL261,’ and tohybrids of, and cultivars derived from the rice cultivar designated‘CL261.’

BACKGROUND ART

Rice is an ancient agricultural crop, and remains one of the world'sprincipal food crops. There are two cultivated species of rice: Oryzasativa L., the Asian rice, and O. glaberrima Steud., the African rice.Oryza sativa L. constitutes virtually all of the world's cultivated riceand is the species grown in the United States. Three major riceproducing regions exist in the United States: the Mississippi Delta(Arkansas, Mississippi, northeast Louisiana, southeast Missouri), theGulf Coast (southwest Louisiana, southeast Texas); and the CentralValley of California. See generally U.S. Pat. No. 6,911,589.

Rice is a semiaquatic crop that benefits from flooded soil conditionsduring part or all of the growing season. In the United States, rice istypically grown on flooded soil to optimize grain yields. Heavy claysoils or silt loam soils with hard pan layers about 30 cm below thesurface are typical rice-producing soils, because they reduce water lossfrom soil percolation. Rice production in the United States can bebroadly categorized as either dry-seeded or water-seeded. In thedry-seeded system, rice is sown into a well-prepared seed bed with agrain drill or by broadcasting the seed and incorporating it with a diskor harrow. Moisture for seed germination comes from irrigation orrainfall. Another method of dry-seeding is to broadcast the seed byairplane into a flooded field, and then to promptly drain the water fromthe field. For the dry-seeded system, when the plants have reachedsufficient size (four- to five-leaf stage), a shallow permanent flood ofwater 5 to 16 cm deep is applied to the field for the remainder of thecrop season. Some rice is grown in upland production systems, withoutflooding.

One method of water-seeding is to soak rice seed for 12 to 36 hours toinitiate germination, and then to broadcast the seed by airplane into aflooded field. The seedlings emerge through a shallow flood, or thewater may be drained from the field for a short period of time toenhance seedling establishment. A shallow flood is then maintained untilthe rice approaches maturity. For both the dry-seeded and water-seededproduction systems, the fields are drained when the crop is mature, andthe rice is harvested 2 to 3 weeks later with large combines.

In rice breeding programs, breeders typically use the same productionsystems that predominate in the region. Thus, a drill-seeded breedingnursery is typically used by breeders in a region where rice isdrill-seeded, and a water-seeded nursery is used in regions wherewater-seeding prevails.

Rice in the United States is classified into three primary market typesby grain size, shape, and endosperm composition: long-grain,medium-grain, and short-grain. Typical U.S. long-grain cultivars cookdry and fluffy when steamed or boiled, while medium- and short-graincultivars cook moist and sticky. Medium grain rice is usually slightlywider than long grain rice and slightly shorter, with a length:widthratio between 2:1 and 3:1.

In the early 1980's about two thirds of Louisiana rice acreage wasplanted with medium grain cultivars. Market demand and the release ofsuperior long grain varieties (e.g., superior yield and superior diseaseresistance) caused medium-grain plantings to decline considerably overthe last 25 years or so. By the mid 1990s, Louisiana rice acreage wasplanted 65 percent long grains, and 35 percent medium grains. For thepast 10 years or so, less than 5 percent of Louisiana rice acreage hasbeen medium grains.

Long-grain cultivars have become the principal varieties grown, not justin Louisiana, but throughout the southern United States in recent years.However, there does remain demand for medium grain production in theregion, and recently that demand has increased substantially. Whilethere are several non-herbicide-resistant, medium-grain cultivarsavailable for the region, such as ‘Jupiter,’ ‘Neptune,’ and ‘Bengal,’there have been no prior releases of any herbicide-resistant, mediumgrain rice cultivars.

There is an unfilled need for herbicide-resistant, medium-grain ricecultivars, particularly those that are well-adapted for growingconditions in the southern United States. Medium grain rice is morecommon in California, but Southern U.S. medium grains differ somewhatfrom those grown in California. Additionally, the weed called “red rice”has been a substantial problem in medium grain rice fields in thesouthern United States. There have been no prior releases of anyherbicide-resistant, medium-grain rice cultivars. There is a particularneed for herbicide-resistant, medium-grain rice cultivars.

Although specific breeding objectives vary somewhat in differentregions, increasing yield is a primary objective in all programs. Grainyield depends, in part, on the number of panicles per unit area, thenumber of fertile florets per panicle, and grain weight per floret.Increases in any or all of these components may help improve yields.Heritable variation exists for each of these components, and breedersmay directly or indirectly select for any of them.

There are numerous steps in the development of any novel, desirableplant germplasm. Plant breeding begins with the analysis and definitionof problems and weaknesses of the current germplasm, the establishmentof program goals, and the definition of specific breeding objectives.The next step is selection (or generation) of germplasm that possess thetraits to meet the program goals. The goal is often to combine in asingle variety an improved combination of desirable traits from two ormore ancestral germplasm lines. These traits may include such things ashigher seed yield, resistance to disease or insects, better stems androots, tolerance to low temperatures, and better agronomiccharacteristics or grain quality.

The choice of breeding and selection methods depends on the mode ofplant reproduction, the heritability of the trait(s) being improved, andthe type of seed that is used commercially (e.g., F₁ hybrid, versus pureline or inbred cultivars). For highly heritable traits, a choice ofsuperior individual plants evaluated at a single location may sometimesbe effective, while for traits with low or more complex heritability,selection is often based on mean values obtained from replicatedevaluations of families of related plants. Selection methods includepedigree selection, modified pedigree selection, mass selection,recurrent selection, and combinations of these methods.

The complexity of inheritance influences the choice of breeding method.Backcross breeding is used to transfer one or a few favorable genes fora highly heritable trait into a desirable cultivar. This approach hasbeen used extensively for breeding disease-resistant cultivars. Variousrecurrent selection techniques are used to improvequantitatively-inherited traits controlled by numerous genes. The use ofrecurrent selection in self-pollinating crops depends on the ease ofpollination, the frequency of successful hybrids from each pollination,and the number of hybrid offspring from each successful cross.

Promising advanced breeding lines are thoroughly tested and compared toappropriate standards in environments representative of the commercialtarget area(s), typically for three or more years. The best lines becomecandidates for new commercial cultivars; those still deficient in a fewtraits may be used as parents to produce new populations for furtherselection.

These processes, which lead ultimately to marketing and distribution ofnew cultivars or hybrids, typically take 8 to 12 years from the time ofthe first cross; they may further rely on (and be delayed by) thedevelopment of improved breeding lines as precursors. Development of newcultivars and hybrids is a time-consuming process that requires preciseforward planning and efficient use of resources. There are neverassurances of a successful outcome.

A particularly difficult task is the identification of individual plantsthat are, indeed, genetically superior. A plant's phenotype results froma complex interaction of genetics and environment. One method foridentifying a genetically superior plant is to observe its performancerelative to other experimental plants and to a widely grown standardcultivar raised in an identical environment. Repeated observations frommultiple locations can help provide a better estimate of its geneticworth.

The goal of rice breeding is to develop new, unique, and superior ricecultivars and hybrids. The breeder initially selects and crosses two ormore parental lines, followed by self pollination and selection,producing many new genetic combinations. The breeder can generatebillions of different genetic combinations via crossing, selfing, andmutation breeding. The traditional breeder has no direct control at themolecular level. Therefore, two traditional breeders workingindependently of one another will never develop the same line, or evenvery similar lines, with the same traits.

Each year, the plant breeder selects germplasm to advance to the nextgeneration. This germplasm is grown under different geographical,climatic, and soil conditions. Further selections are then made, duringand at the end of the growing season. The resulting cultivars (orhybrids) and their characteristics are inherently unpredictable. This isbecause the traditional breeder's selection occurs in uniqueenvironments, with no control at the molecular level, and withpotentially billions of different possible genetic combinations beinggenerated. A breeder cannot predict the final resulting line, exceptpossibly in a very gross and generic fashion. Further, the same breedermay not produce the same cultivar twice, even starting with the sameparental lines, using the same selection techniques. This uncontrollablevariation results in substantial effort and expenditures in developingsuperior new rice cultivars (or hybrids); and makes each new cultivar(or hybrid) novel and unpredictable.

The selection of superior hybrid crosses is conducted slightlydifferently. Hybrid seed is typically produced by manual crosses betweenselected male-fertile parents or by using genetic male sterilitysystems. These hybrids are typically selected for single gene traitsthat unambiguously indicate that a plant is indeed an F₁ hybrid that hasinherited traits from both presumptive parents, particularly the maleparent (since rice normally self-fertilizes). Such traits might include,for example, a semi dwarf plant type, pubescence, awns, or apiculuscolor. Additional data on parental lines, as well as the phenotype ofthe hybrid, influence the breeder's decision whether to continue with aparticular hybrid cross or an analogous cross, using related parentallines.

Pedigree breeding and recurrent selection breeding methods are sometimesused to develop cultivars from breeding populations. These breedingmethods combine desirable traits from two or more cultivars or othergermplasm sources into breeding pools from which cultivars are developedby selfing and selection of desired phenotypes. The new cultivars areevaluated to determine commercial potential.

Pedigree breeding is often used to improve self-pollinating crops. Twoparents possessing favorable, complementary traits are crossed toproduce F₁ plants. An F₂ population is produced by selfing one or moreF₁s. Selection of the superior individual plants may begin in the F₂ (orlater) generation. Then, beginning in the F₃ (or other subsequent)generation, individual plants are selected. Replicated testing ofpanicle rows from the selected plants can begin in the F₄ (or othersubsequent) generation, both to fix the desired traits and to improvethe effectiveness of selection for traits that have low heritability. Atan advanced stage of inbreeding (e.g., F₆ or F₇), the best lines ormixtures of phenotypically-similar lines are tested for potentialrelease as new cultivars.

Mass and recurrent selection methods can also be used to improvepopulations of either self- or cross-pollinating crops. A geneticallyvariable population of heterozygous individuals is either identified orcreated by intercrossing several different parents. The best offspringplants are selected based on individual superiority, outstandingprogeny, or excellent combining ability. The selected plants areintercrossed to produce a new population in which further cycles ofselection are continued.

Backcross breeding is often used to transfer genes for a simplyinherited, highly heritable trait into a desirable homozygous cultivaror inbred line, which is the recurrent parent. The source of the traitto be transferred is called the donor parent. The resulting plant shouldideally have the attributes of the recurrent parent (e.g., cultivar) andthe desired new trait transferred from the donor parent. After theinitial cross, individuals possessing the desired donor phenotype (e.g.,disease resistance, insect resistance, herbicide tolerance) are selectedand repeatedly crossed (backcrossed) to the recurrent parent.

The single-seed descent procedure in the strict sense refers to plantinga segregating population, harvesting a sample of one seed per plant, andusing the one-seed sample to plant the next generation. When thepopulation has been advanced from the F₂ generation to the desired levelof inbreeding, the plants from which lines are derived will each traceto different F₂ individuals. The number of plants in a populationdeclines each generation due to failure of some seeds to germinate orsome plants to produce at least one seed. As a result, not all of the F₂plants originally sampled in the population will be represented by aprogeny when generation advance is completed.

In a multiple-seed procedure, the breeder harvests one or more seedsfrom each plant in a population and threshes them together to form abulk. Part of the bulk is used to plant the next generation and part isput in reserve. The procedure has been referred to as modifiedsingle-seed descent or the pod-bulk technique. The multiple-seedprocedure has been used to save labor at harvest. It is considerablyfaster to thresh panicles by machine than to remove one seed from eachby hand as in the single-seed procedure. The multiple-seed procedurealso makes it possible to plant the same number of seeds from apopulation for each generation of inbreeding. Enough seeds are harvestedto compensate for plants that did not germinate or produce seed.

Other common and less-common breeding methods are known and used in theart. See, e.g., R. W. Allard, Principles of Plant Breeding (John Wileyand Sons, Inc., New York, N.Y., 1967); N. W. Simmonds, Principles ofCrop Improvement (Longman, London, 1979); J. Sneep et al., PlantBreeding Perspectives (Pudoc, Wageningen, 1979); and W. R. Fehr,Principles of Cultivar Development: Theory and Technique (MacmillanPub., New York, N.Y., 1987).

Proper testing should detect any major faults and establish the level ofsuperiority or improvement over current cultivars. In addition toshowing superior performance, there must be a demand for a new cultivaror hybrid that is compatible with industry standards or that creates anew market. The introduction of a new cultivar or hybrid may incuradditional costs to the seed producer, the grower, processor andconsumer for such things as special advertising and marketing, alteredseed and commercial production practices, and new product utilization.The testing preceding release of a new cultivar or hybrid should takeinto consideration research and development costs as well as technicalsuperiority of the final cultivar or hybrid.

In recent years, a few herbicide-tolerant rice varieties and hybridshave been successfully introduced to the market. See U.S. Pat. Nos.5,545,822; 5,736,629; 5,773,703; 5,773,704; 5,952,553; 6,274,796;6,943,280; 7,019,196; 7,345,221; 7,399,905; and 7,495,153; publishedInternational Patent Applications WO 00/27182 and WO 01/85970; andpublished U.S. patent application 2007/0061915. These herbicide-tolerantrice plants are resistant to or tolerant of herbicides that normallyinhibit the growth of rice plants. Thus, rice growers now can controlweeds that previously were difficult to control in rice fields,including “red rice.” “Red rice” is a weedy relative of cultivated rice,and had previously been difficult to control because it actually belongsto the same species as cultivated rice. Only recently, when herbicidetolerant rice became available, did it become possible to control redrice with herbicides in fields where cultivated rice was growingcontemporaneously. There are currently only a very limited number ofherbicide-tolerant cultivars and hybrids available commercially. Thereis a continuing need for new herbicide-tolerant cultivars andhybrids—that is, rice plants that not only express a desiredherbicide-tolerant phenotype, but that also possess other agronomicallydesirable characteristics. Additional herbicide-tolerant cultivars andhybrids will provide rice growers greater flexibility in planting andmanaging crops.

DISCLOSURE OF THE INVENTION

I have discovered a novel, herbicide-resistant, high yielding, earlymaturing, short stature, medium-grain rice cultivar designated ‘CL261.’This invention also pertains to methods for producing a hybrid or newvariety by crossing the rice variety ‘CL261’ with another rice line, oneor more times. Thus any such methods using the rice variety ‘CL261’ areaspects of this invention, including backcrossing, hybrid production,crosses to populations, and other breeding methods involving ‘CL261.’Hybrid plants produced using the rice variety ‘CL261’ as a parent arealso within the scope of this invention. Optionally, either parent can,through routine manipulation of cytoplasmic or other factors throughtechniques known in the art, be produced in a male-sterile form.

In another embodiment, this invention allows for single-gene convertedplants of ‘CL261.’ The single transferred gene may be a dominant orrecessive allele. Preferably, the single transferred gene confers atrait such as resistance to insects, one or more bacterial, fungal orviral diseases, male fertility or sterility, enhanced nutritionalquality, enhanced processing qualities, or an additional source ofherbicide resistance. The single gene may be a naturally occurring ricegene or a transgene introduced through genetic engineering techniquesknown in the art. The single gene also may be introduced throughtraditional backcrossing techniques or genetic transformation techniquesknown in the art.

In another embodiment, this invention provides regenerable cells for usein tissue culture of rice plant ‘CL261.’ The tissue culture may allowfor regeneration of plants having physiological and morphologicalcharacteristics of rice plant ‘CL261’ and of regenerating plants havingsubstantially the same genotype as rice plant ‘CL261.’ Tissue culturetechniques for rice are known in the art. The regenerable cells intissue culture may be derived from sources such as embryos, protoplasts,meristematic cells, callus, pollen, leaves, anthers, root tips, flowers,seeds, panicles, or stems. In addition, the invention provides riceplants regenerated from such tissue cultures.

In other embodiments, the present invention provides a method forcontrolling weeds in the vicinity of rice. The method comprisescontacting the rice with a herbicide, wherein said rice belongs to anyof (a) variety ‘CL261’ or (b) a hybrid, derivative, or progeny of‘CL261’ that expresses the imidazolinone herbicide resistancecharacteristics of ‘CL261.’

In some embodiments, the herbicide is an imidazolinone herbicide, asulfonylurea herbicide, or a combination thereof.

In one embodiment, the rice is a rice plant and said contactingcomprises applying the herbicide in the vicinity of the rice plant.

In another embodiment, the herbicide is applied to weeds in the vicinityof the rice plant.

In still further embodiments, the rice is a rice seed and saidcontacting comprises applying the herbicide to the rice seed.

In some embodiments, the present invention provides a method fortreating rice. The method comprises contacting the rice with anagronomically acceptable composition, wherein said rice belongs to anyof (a) variety ‘CL261’ or (b) a hybrid, derivative, or progeny of‘CL261’ that expresses the imidazolinone herbicide resistancecharacteristics of ‘CL261.’

In one embodiment, the agronomically acceptable composition comprises atleast one agronomically acceptable active ingredient.

In another embodiment, the agronomically acceptable active ingredient isselected from the group consisting of fungicides, insecticides,antibiotics, stress tolerance-enhancing compounds, growth promoters,herbicides, molluscicides, rodenticides, and animal repellants, andcombinations thereof.

DEFINITIONS

The following definitions apply throughout the specification and claims,unless context clearly indicates otherwise:

“Days to 50% heading.” Average number of days from seeding to the daywhen 50% of all panicles are exerted at least partially through the leafsheath. A measure of maturity.

“Grain Yield.” Grain yield is measured in pounds per acre, at 12.0%moisture. Grain yield depends on a number of factors, including thenumber of panicles per unit area, the number of fertile florets perpanicle, and grain weight per floret.

“Lodging Percent.” Lodging is a subjectively measured rating, and is thepercentage of plant stems leaning or fallen completely to the groundbefore harvest.

“Grain Length (L).” Length of a rice grain, or average length, measuredin millimeters.

“Grain Width (W).” Width of a rice grain, or average width, measured inmillimeters.

“Length/Width (L/W) Ratio.” This ratio is determined by dividing theaverage length (L) by the average width (W).

“1000 Grain Wt.” The weight of 1000 rice grains, measured in grams.

“Harvest Moisture.” The percentage moisture in the grain when harvested.

“Plant Height.” Plant height in centimeters, measured from soil surfaceto the tip of the extended panicle at harvest.

“Apparent Amylose Percent.” The percentage of the endosperm starch ofmilled rice that is amylose. The apparent amylose percent is animportant grain characteristic that affects cooking behavior. Standardlong grains contain 20 to 23 percent amylose. Rexmont-type long grainscontain 24 to 25 percent amylose. Short and medium grains contain 13 to19 percent amylose. Waxy rice contains zero percent amylose. Amylosevalues, like most characteristics of rice, depend on the environment.“Apparent” refers to the procedure for determining amylose, which mayalso involve measuring some long chain amylopectin molecules that bindto some of the amylose molecules. These amylopectin molecules actuallyact similar to amylose in determining the relative hard or soft cookingcharacteristics.

“Alkali Spreading Value.” An index that measures the extent ofdisintegration of the milled rice kernel when in contact with dilutealkali solution. An indicator of gelatinization temperature. Standardlong grains have a 3 to 5 Alkali Spreading Value (intermediategelatinization temperature).

“Peak Viscosity.” The maximum viscosity attained during heating when astandardized, instrument-specific protocol is applied to a defined riceflour-water slurry.

“Trough Viscosity.” The minimum viscosity after the peak, normallyoccurring when the sample starts to cool.

“Final Viscosity.” Viscosity at the end of the test or cold paste.

“Breakdown.” The peak viscosity minus the hot paste viscosity.

“Setback.” Setback 1 is the final viscosity minus the trough viscosity.Setback 2 is the final viscosity minus the peak viscosity.

“RVA Viscosity.” Viscosity, as measured by a Rapid Visco Analyzer, is anew but widely used laboratory instrument to examine paste viscosity orthickening ability of milled rice during the cooking process.

“Hot Paste Viscosity.” Viscosity measure of rice flour/water slurryafter being heated to 95° C. Lower values indicate softer and stickiercooking types of rice.

“Cool Paste Viscosity.” Viscosity measure of rice flour/water slurryafter being heated to 95° C. and uniformly cooled to 50° C. Values lessthan 200 indicate softer cooking types of rice.

“Allele.” An allele is any of one or more alternate forms of the samegene. In a diploid cell or organism, the two alleles of a given geneoccupy corresponding loci on a pair of homologous chromosomes.

“Backcrossing.” Backcrossing is a process in which a breeder repeatedlycrosses hybrid progeny back to one of the parents, for example, crossinga first generation hybrid F₁ with one of the parental genotypes of theF₁ hybrid, and then crossing a second generation hybrid F₂ with the sameparental genotype, and so forth.

“Essentially all the physiological and morphological characteristics.” Aplant having “essentially all the physiological and morphologicalcharacteristics” of a specified plant refers to a plant having the samegeneral physiological and morphological characteristics, except forthose characteristics derived from a particular converted gene.

“Quantitative Trait Loci (QTL).” Quantitative trait loci (QTL) refer togenetic loci that to some degree control numerically measurable traits,generally traits that are continuously distributed.

“Regeneration.” Regeneration refers to the development of a plant fromtissue culture.

“Single Gene Converted (Conversion).” Single gene converted (conversion)includes plants developed by backcrossing wherein essentially all of thedesired morphological and physiological characteristics of a parentalvariety are recovered, while retaining a single gene transferred intothe variety via crossing and backcrossing. The term can also refer tothe introduction of a single gene through genetic engineering techniquesknown in the art.

MODES FOR CARRYING OUT THE INVENTION

‘CL261’ is a is a very high yielding, early maturing, short staturemedium-grain rice variety that contains, by common ancestry, the samegene for herbicide resistance as that found in the cultivar ‘CL161.’ Thepedigree for this line is ‘Bengal’/‘CL161.’ ‘CL161’ is animazethapyr-resistant mutant derived from the variety Cypress. See U.S.Pat. No. 7,019,196. ‘CL261’ is highly resistant to imidazolinoneherbicides, including but not limited to imazethapyr and imazamox.‘CL261’ has a clear grain, with not much chalk. Its bold grainapproaches the size of that from the conventional medium-grain varieties‘Neptune’ and ‘Bengal.’

‘CL261’ was originally selected from the cross ‘Bengal’/‘CL161,’ made atthe Louisiana State University Rice Research Station in Crowley, La. Theline originated as an F5 bulk of a single progeny row. ‘CL261’ has ashort stature, and is moderately resistant to lodging. It averaged 37inches in height during two years of testing, as compared to 37 and 33inches for cultivars ‘CL151’ and ‘CL131,’ respectively. ‘CL261’ hasaveraged 81 days from emergence to 50% heading, compared to 79 days forboth of ‘CL151’ and ‘CL131.’ The leaves, lemma, and palea of CL261 areglabrous. The spikelet is straw-colored. The apiculus is light purple atheading, and the color fades as the grains approach maturity. The grainis non-aromatic. ‘CL261’ is susceptible to sheath blight and blast, andis moderately susceptible to straighthead disorder.

After the initial cross was made, the line was harvested and selectedthrough early generations for phenotypic superiority for characteristicssuch as short plant architecture, grain shape and uniformity, seedlingvigor, tiller number, and grain size. In later generations (seedincrease), the line was selected for uniformity and purity both withinand between panicle rows. Variants removed from seed-increase fields of‘CL261’ were primarily taller or later plants. Other variants includedany combination of the following: leaf pubescence, earlier, shorter,long grain, gold hull, lighter colored leaf, and variegated leaf. Theoverall incidence of variants less than 1 per 5,000 plants. Foundationseed rice was eventually grown beginning with the F₇ generation. Seedfrom the F₅, F₆, and F₇ generations were entered into an experimentalline testing program, and were also tested at several locations inLouisiana rice producing areas. ‘CL261’ has been observed to be stablefor at least three generations.

Across testing in several trials at multiple Louisiana locations duringa three-year period, overall average grain yield was 7871 lb/A for‘CL261,’ compared to 7700 lb/A for ‘CL131’ and 8683 lb/A for ‘CL151.’

Variety Description Information

Rice cultivar ‘CL261’ was observed to possess the followingmorphological and other characteristics, based on averages of testsconducted at multiple locations across the state of Louisiana duringthree growing seasons; data for varieties ‘CL131’ and ‘CL151’ are shownfor comparison:

Number Trait Performance of Tests ‘CL261’ ‘CL131’ ‘CL151’ Main CropYield (lb./A) 7871 7700 8683 6 Ratoon Crop Yield (lb./A) Whole ricemilling yield (%) 67.4 65.6 63.8 5 Total rice milling yield (%) 70.871.3 70.0 5 Seedling Vigor (Subjective rating of seedling vigor— 4 4 4 5scale 1-9, with lower numbers indicating higher levels of vigor) MeanPlant Height (inches) 37 33 37 6 Mean Number of Days to 50% Heading 8179 79 6 Reaction to Narrow Brown Leaf Spot (Cercospora 4.8 3.8 janseana)(0 = very resistant, 9 = very susceptible) Reaction to Leaf Smut(Entyloma oryzae) (0 = very resistant, 9 = very susceptible) Reaction toBrown Leaf Spot (Helminthosporium oryzae) (0 = very resistant, 9 = verysusceptible) Reaction to Panicle Blight (B. gladioli) (0 = very 6.3 5.3resistant, 9 = very susceptible) Reaction to Sheath Blight (Rhizoctoniasolani) (0 = 7.5 6.5 very resistant, 9 = very susceptible) Reaction toStraighthead (0 = very resistant, 9 = 4.9 6.7 7.0 2 very susceptible)‘CL261’ ‘Jupiter’ ‘Neptune’ Length-Rough (mm) 7.40 7.87 7.95 Width-Rough(mm) 3.22 3.20 3.25 L/W Ratio-Rough 2.30 2.46 2.45 Length-Brown (mm)5.75 5.85 5.97 Width-Brown (mm) 2.89 2.86 2.85 L/W Ratio-Brown 1.99 2.052.09 Length-Milled (mm) 5.31 5.47 5.62 Width-Milled (mm) 2.66 2.68 2.55L/W Ratio-Milled 2.00 2.04 2.20

CULM:

Angle (degrees from perpendicular after flowering): Erect (less than30°)

Length: 94 cm (same as CL151; 10 cm longer than CL131)

Internode color (After flowering): Green

Strength (Lodging resistance): Moderately strong

FLAG LEAF (at maturity):

Length: 21 cm

Width: 10 mm

Pubescence: Glabrous

Leaf Angle (after heading): Intermediate

Blade Color (at heading): Dark Green

Basal Leaf Sheath Color (at heading): Green

LIGULE:

Length: 2 cm

Color (Late vegetative state): White

Shape: Cleft

Collar Color (Late vegetative stage): Pale Green

Auricle Color (Late vegetative stage): Pale Green

PANICLE:

Length: 19 cm

Type: Intermediate

Secondary Branching Heavy

Exsertion (near maturity): >90%

Shattering: (<5%)

Threshability: Intermediate

GRAIN (Spikelet):

Awns (After full heading): Short and Partly Awned

Apiculus Color (at maturity): Purple

Apiculus Color (After full heading): Purple

Stigma Color White

Lemma and Palea Color (at maturity): Straw

Lemma and Palea Pubescence: Glabrous

Spikelet Sterility (at maturity): (<10%=highly fertile)

GRAIN (Seed):

Seed Coat (bran) Color: Light Brown

Endosperm Type Nonglutinous (Non-Waxy)

Endosperm Translucency Clear

Endosperm Chalkiness: (small, less than 10% of sample)

Scent: Nonscented

Shape Class (Length/width ratio):

Paddy—Medium (2.3-3.3) (viz, 2.30)

Brown—Short (2.0 or less) (viz, 1.99)

Milled—Medium (2.0-2.9) (viz, 2.00)

Length Width Thickness L/W 1000 Grains Grain Form: (mm) (mm) (mm) Ratio(grams) Paddy 7.40 3.22 1.99 2.30 24.6 Brown 5.75 2.89 1.77 1.99 20.1Milled 5.31 2.66 1.70 2.00 16.9Milling quality (% hulls): 20Milling yield (% white kernel (head) rice to rough rice): 66-71

Protein (NIR): 7.5%

Amylose: 18.9%

Alkali Spreading value: 7.0 (1.7% KOH Solution)

Gelatination Temperature Type: Intermediate

RESISTANCE TO LOW TEMPERATURE:

Germination and Seedling Vigor: Medium

Flowering (Spikelet fertility): High

SEEDLING VIGOR NOT RELATED TO LOW TEMPERATURE:

Vigor: High

INSECT RESISTANCE: Susceptible to Rice Water Weevil (Lissorhoptrusoryzophilus), and to Rice stink Bug (Oegalus pugnax)

The variety is resistant to imidazolinone herbicides. The herbicideresistance profile is essentially the same as that of ‘CL161,’ beingderived from common ancestry. The herbicide tolerance allows ‘CL261,’its hybrids, and derived varieties to be used with Clearfield™ ricetechnology and herbicides, including among others imazethapyr andimazamox, for the selective control of weeds, including red rice. Seegenerally U.S. Pat. No. 6,943,280.

Herbicide Tolerance and Susceptibility Characteristics:

The variety is tolerant to some herbicides, and susceptible to someherbicides, that normally inhibit the growth of rice plants. Amongothers, the herbicide tolerance and susceptibility characteristics of‘CL261’ include or are expected to include the following. Thesecharacteristics are in some cases based on actual observations to date,and in other cases reflect assumptions based on common ancestry with‘CL161’:

-   -   ‘CL261’ expresses a mutant acetohydroxyacid synthase whose        enzymatic activity is directly resistant to normally-inhibitory        levels of a herbicidally-effective imidazolinone;    -   ‘CL261’ is resistant to each of the following imidazolinone        herbicides, at levels of the imidazolinone herbicides that would        normally inhibit the growth of a rice plant: imazethapyr,        imazapic, imazaquin, imazamox, and imazapyr;    -   ‘CL261’ is resistant to each of the following sulfonylurea        herbicides, at levels of the sulfonylurea herbicides that would        normally inhibit the growth of a rice plant: nicosulfuron,        metsulfuron methyl, thifensulfuron methyl, and tribenuron        methyl;    -   ‘CL261’ is sensitive to each of the following sulfonylurea        herbicides, at levels of the sulfonylurea herbicides that would        normally inhibit the growth of a rice plant: sulfometuron        methyl, chlorimuron ethyl, and rimsulfuron.

This invention is also directed to methods for producing a rice plant bycrossing a first parent rice plant with a second parent rice plant,wherein the first or second rice plant is a rice plant from the line‘CL261.’ Further, both first and second parent rice plants may be fromthe cultivar ‘CL261,’ although it is preferred that one of the parentsbe different. Methods using the cultivar ‘CL261’ are part of thisinvention, including crossing, selfing, backcrossing, hybrid breeding,crossing to populations, the other breeding methods discussed earlier inthis specification, and other breeding methods known to those of skillin the art. Any plants produced using cultivar ‘CL261’ as a parent orancestor are within the scope of this invention. The other parents orother lines used in such breeding programs may be any of the wide numberof rice varieties, cultivars, populations, experimental lines, and othersources of rice germplasm known in the art.

For example, this invention includes methods for producing afirst-generation hybrid rice plant by crossing a first parent rice plantwith a second parent rice plant, wherein either the first or secondparent rice plant is ‘CL261.’ Further, this invention is also directedto methods for producing a hybrid rice line derived from ‘CL261’ bycrossing ‘CL261’ with a second rice plant, and growing the progeny seed.The crossing and growing steps may be repeated any number of times.Breeding methods using the rice line ‘CL261’ are considered part of thisinvention, not only backcrossing and hybrid production, but alsoselfing, crosses to populations, and other breeding methods known in theart.

Optionally, either of the parents in such a cross, ‘CL261’ or the otherparent, may be produced in male-sterile form, using techniques known inthe art.

FURTHER EMBODIMENTS OF THE INVENTION

As used herein, the term “plant” includes plant cells, plantprotoplasts, plant cells of tissue culture from which rice plants can beregenerated, plant calli, plant clumps, and plant cells that are intactin plants or parts of plants, such as pollen, flowers, embryos, ovules,seeds, pods, leaves, stems, anthers and the like. Thus, another aspectof this invention is to provide for cells that, upon growth anddifferentiation, produce a cultivar having essentially all of thephysiological and morphological characteristics of ‘CL261.’

Techniques for transforming with and expressing desired structural genesand cultured cells are known in the art. Also, as known in the art, ricemay be transformed and regenerated such that whole plants containing andexpressing desired genes under regulatory control are obtained. Generaldescriptions of plant expression vectors and reporter genes andtransformation protocols can be found, for example, in Gruber et al.,“Vectors for Plant Transformation, in Methods in Plant Molecular Biology& Biotechnology” in Glich et al. (Eds. pp. 89-119, CRC Press, 1993). Forexample, expression vectors and gene cassettes with the GUS reporter areavailable from Clone Tech Laboratories, Inc. (Palo Alto, Calif.), andexpression vectors and gene cassettes with luciferase reporter areavailable from Promega Corp. (Madison, Wis.). General methods ofculturing plant tissues are provided, for example, by Maki et al.,“Procedures for Introducing Foreign DNA into Plants” in Methods in PlantMolecular Biology & Biotechnology, Glich et al., (Eds. pp. 67-88 CRCPress, 1993); by Phillips et al., “Cell-Tissue Culture and In-VitroManipulation” in Corn & Corn Improvement, 3rd Edition; and by Sprague etal., (Eds. pp. 345-387) American Society of Agronomy Inc., 1988. Methodsof introducing expression vectors into plant tissue include the directinfection or co-cultivation of plant cells with Agrobacteriumtumefaciens, Horsch et al., Science, 227:1229 (1985). Descriptions ofAgrobacterium vectors systems and methods for Agrobacterium-mediatedgene transfer are provided by Gruber et al., supra.

Useful methods include but are not limited to expression vectorsintroduced into plant tissues using a direct gene transfer method suchas microprojectile-mediated delivery, DNA injection, electroporation andthe like. More preferably expression vectors are introduced into planttissues using the microprojectile media delivery with biolistic device-or Agrobacterium-mediated transformation. Transformed plants obtainedwith the germplasm of ‘CL261’ are intended to be within the scope ofthis invention.

The present invention also provides rice plants regenerated from atissue culture of the ‘CL261’ variety or hybrid plant. As is known inthe art, tissue culture can be used for the in vitro regeneration of arice plant. For example, see Chu, Q. R. et al. (1999) “Use of bridgingparents with high anther culturability to improve plant regeneration andbreeding value in rice,” Rice Biotechnology Quarterly, 38:25-26; Chu, Q.R. et al., “A novel plant regeneration medium for rice anther culture ofSouthern U.S. crosses,” Rice Biotechnology Quarterly, 35:15-16 (1998);Chu, Q. R. et al., “A novel basal medium for embryogenic callusinduction of Southern US crosses,” Rice Biotechnology Quarterly,32:19-20 (1997); and Oono, K., “Broadening the Genetic Variability ByTissue Culture Methods,” Jap. J. Breed., 33 (Supp. 2), 306-307 (1983).Thus, another aspect of this invention is to provide cells that, upongrowth and differentiation, produce rice plants having all, oressentially all, of the physiological and morphological characteristicsof variety ‘CL261.’

Unless context clearly indicates otherwise, references in thespecification and claims to ‘CL261’ should be understood also to includesingle gene conversions of ‘CL261.’ male sterility, other sources ofherbicide resistance, resistance for bacterial, fungal, or viraldisease, insect resistance, male fertility, enhanced nutritionalquality, industrial usage, yield stability and yield enhancement.

Duncan et al., Planta, 165:322-332 (1985) reflects that 97% of theplants cultured that produced callus were capable of plant regeneration.Subsequent experiments with both inbreds and hybrids produced 91%regenerable callus that produced plants. In a further study, Songstad etal., Plant Cell Reports, 7:262-265 (1988) reported several mediaadditions that enhanced regenerability of callus of two inbred lines.Other published reports also indicate that “nontraditional” tissues arecapable of producing somatic embryogenesis and plant regeneration. K. P.Rao et al., Maize Genetics Cooperation Newsletter, 60:64-65 (1986),refers to somatic embryogenesis from glume callus cultures and B. V.Conger et al., Plant Cell Reports, 6:345-347 (1987) reported somaticembryogenesis from the tissue cultures of corn leaf segments. Thesemethods of obtaining plants are routinely used with a high rate ofsuccess.

Tissue culture of corn is described in European Patent Application No.160,390. Corn tissue culture procedures, which may be adapted for usewith rice, are also described in Green et al., “Plant Regeneration inTissue Culture of Maize,” Maize for Biological Research (Plant MolecularBiology Association, Charlottesville, Va., pp. 367-372, 1982) and inDuncan et al., “The Production of Callus Capable of Plant Regenerationfrom Immature Embryos of Numerous Zea Mays Genotypes,” 165 Planta,322:332 (1985). Thus, another aspect of this invention is to providecells that, upon growth and differentiation, produce rice plants havingall, or essentially all, of the physiological and morphologicalcharacteristics of hybrid rice line ‘CL261.’ See T. P. Croughan et al.,(Springer-Verlag, Berlin, 1991) Rice (Oryza sativa. L): Establishment ofCallus Culture and the regeneration of Plants, in Biotechnology inAgriculture and Forestry (19-37).

With the advent of molecular biological techniques that allow theisolation and characterization of genes that encode specific proteinproducts, it is now possible to routinely engineer plant genomes toincorporate and express foreign genes, or additional or modifiedversions of native, or endogenous, genes (perhaps driven by differentpromoters) in order to alter the traits of a plant in a specific manner.Such foreign, additional, and modified genes are herein referred tocollectively as “transgenes.” Over the last 15 to 20 years, severalmethods for producing transgenic plants have been developed, and thepresent invention, in particular embodiments, also relates totransformed versions of ‘CL261.’

An expression vector is constructed that will function in plant cells.Such a vector comprises a DNA coding sequence under the control of oroperatively linked to a regulatory element (e.g., a promoter). Theexpression vector may contain one or more such operably linked codingsequence/regulatory element combinations. The vector(s) may be in theform of a plasmid, and can be used alone or in combination with otherplasmids to provide transformed rice plants.

Expression Vectors

Expression vectors commonly include at least one genetic “marker,”operably linked to a regulatory element (e.g., a promoter) that allowstransformed cells containing the marker to be either recovered bynegative selection, i.e., inhibiting growth of cells that do not containthe selectable marker gene, or by positive selection, i.e., screeningfor the product encoded by the genetic marker. Many commonly usedselectable marker genes for plant transformation are known in the art,and include, for example, genes that code for enzymes that metabolicallydetoxify a selective chemical inhibitor such as an antibiotic or aherbicide, or genes that encode an altered target that is insensitive tosuch an inhibitor. Positive selection methods are also known in the art.

For example, a commonly used selectable marker gene for planttransformation is that for neomycin phosphotransferase II (nptII),isolated from transposon Tn5, whose expression confers resistance tokanamycin. See Fraley et al., Proc. Natl. Acad. Sci. U.S.A., 80:4803(1983). Another commonly used selectable marker gene is the hygromycinphosphotransferase gene, which confers resistance to the antibiotichygromycin. See Vanden Elzen et al., Plant Mol. Biol., 5:299 (1985).

Additional selectable marker genes of bacterial origin that conferresistance to one or more antibiotics include gentamycin acetyltransferase, streptomycin phosphotransferase, aminoglycoside-3′-adenyltransferase, and the bleomycin resistance determinant. Hayford et al.,Plant Physiol., 86:1216 (1988), Jones et al., Mol. Gen. Genet., 210:86(1987), Svab et al., Plant Mol. Biol., 14:197 (1990); Plant Mol. Biol.,7:171 (1986). Other selectable marker genes confer resistance toherbicides such as glyphosate, glufosinate, or broxynil. Comai et al.,Nature, 317:741-744 (1985); Gordon-Kamm et al., Plant Cell, 2:603-618(1990); and Stalker et al., Science, 242:419-423 (1988).

Selectable marker genes for plant transformation of non-bacterial origininclude, for example, mouse dihydrofolate reductase, plant5-enolpyruvylshikimate-3-phosphate synthase, and plant acetolactatesynthase. Eichholtz et al., Somatic Cell Mol. Genet. 13:67 (1987); Shahet al., Science, 233:478 (1986); and Charest et al., Plant Cell Rep.,8:643 (1990).

Another class of marker genes for plant transformation employs screeningof presumptively transformed plant cells, rather than selection forresistance to a toxic substance such as an antibiotic. These markergenes are particularly useful to quantify or visualize the spatialpattern of expression of a gene in specific tissues, and are frequentlyreferred to as reporter genes because they may be fused to the targetgene or regulatory sequence. Commonly used reporter genes includeglucuronidase (GUS), galactosidase, luciferase, chloramphenicol, andacetyltransferase. See Jefferson, R. A., Plant Mol. Biol. Rep., 5:387(1987); Teeri et al., EMBO J., 8:343 (1989); Koncz et al., Proc. Natl.Acad. Sci. U.S.A., 84:131 (1987); and DeBlock et al., EMBO J., 3:1681(1984). Another approach to identifying relatively rare transformationevents has been the use of a gene that encodes a dominant constitutiveregulator of the Zea mays anthocyanin pigmentation pathway. Ludwig etal., Science, 247:449 (1990).

The Green Fluorescent Protein (GFP) gene has been used as a marker forgene expression in prokaryotic and eukaryotic cells. See Chalfie et al.,Science, 263:802 (1994). GFP and mutants of GFP may be used asscreenable markers.

Genes included in expression vectors are driven by a nucleotide sequencecomprising a regulatory element, for example, a promoter. Many suitablepromoters are known in the art, as are other regulatory elements thatmay be used either alone or in combination with promoters.

As used herein, “promoter” refers to a region of DNA upstream from thetranscription initiation site, a region that is involved in recognitionand binding of RNA polymerase and other proteins to initiatetranscription. A “plant promoter” is a promoter capable of initiatingtranscription in plant cells. Examples of promoters under developmentalcontrol include promoters that preferentially initiate transcription incertain tissues, such as leaves, roots, seeds, fibers, xylem vessels,tracheids, or sclerenchyma. Such promoters are referred to as“tissue-preferred.” Promoters that initiate transcription only incertain tissue are referred to as “tissue-specific.” A “cell type”specific promoter primarily drives expression in certain cell types inone or more organs, for example, vascular cells in roots or leaves. An“inducible” promoter is a promoter that is under environmental control.Examples of environmental conditions that may induce transcription byinducible promoters include anaerobic conditions or the presence oflight. Tissue-specific, tissue-preferred, cell type specific, andinducible promoters are examples of “non-constitutive” promoters. A“constitutive” promoter is a promoter that is generally active undermost environmental conditions.

A. Inducible Promoters

An inducible promoter is operably linked to a gene for expression inrice. Optionally, the inducible promoter is operably linked to anucleotide sequence encoding a signal sequence that is operably linkedto a gene for expression in rice. With an inducible promoter the rate oftranscription increases in response to an inducing agent.

Any suitable inducible promoter may be used in the present invention.See Ward et al., Plant Mol. Biol., 22:361-366 (1993). Examples includethose from the ACEI system, which responds to copper, Meft et al., PNAS,90:4567-4571 (1993); In2 gene from maize, which responds tobenzenesulfonamide herbicide safeners, Hershey et al., Mol. Gen.Genetics, 227:229-237 (1991); Gatz et al., Mol. Gen. Genetics, 243:32-38(1994); and Tet repressor from Tn10, Gatz, Mol. Gen. Genetics,227:229-237 (1991). A preferred inducible promoter is one that respondsto an inducing agent to which plants do not normally respond, forexample, the inducible promoter from a steroid hormone gene, thetranscriptional activity of which is induced by a glucocorticosteroidhormone. See Schena et al., Proc. Natl. Acad. Sci., U.S.A. 88:0421(1991).

B. Constitutive Promoters

A constitutive promoter is operably linked to a gene for expression inrice, or the constitutive promoter is operably linked to a nucleotidesequence encoding a signal sequence that is operably linked to a genefor expression in rice.

Constitutive promoters may also be used in the instant invention.Examples include promoters from plant viruses such as the ³⁵S promoterfrom cauliflower mosaic virus, Odell et al., Nature, 313:810-812 (1985),and the promoters from the rice actin gene, McElroy et al., Plant Cell,2:163-171 (1990); ubiquitin, Christensen et al., Plant Mol. Biol.,12:619-632 (1989) and Christensen et al., Plant Mol. Biol. 18:675-689(1992); pEMU, Last et al., Theor. Appl. Genet., 81:581-588 (1991); MAS,Velten et al., EMBO J., 3:2723-2730 (1984); and maize H3 histone,Lepetit et al., Mol. Gen. Genetics, 231:276-285 (1992) and Atanassova etal., Plant Journal, 2 (3): 291-300 (1992).

An ALS (AHAS) promoter, such as the XbaI/NcoI fragment 5′ from theBrassica napus ALS3 structural gene (or a nucleotide sequence similar tosaid XbaI/NcoI fragment), may be used as a constitutive promoter. SeePCT Application WO 96/30530. The promoter from a rice ALS (AHAS) genemay also be used. See the sequences disclosed in PCT Application WO01/85970; and U.S. Pat. No. 6,943,280.

C. Tissue-Specific or Tissue-Preferred Promoters

A tissue-specific promoter is operably linked to a gene for expressionin rice. Optionally, the tissue-specific promoter is operably linked toa nucleotide sequence encoding a signal sequence that is operably linkedto a gene for expression in rice. Transformed plants produce theexpression product of the transgene exclusively, or preferentially, inspecific tissue(s).

Any tissue-specific or tissue-preferred promoter may be used in theinstant invention. Examples of tissue-specific or tissue-preferredpromoters include those from the phaseolin gene, Murai et al., Science,23:476-482 (1983), and Sengupta-Gopalan et al., Proc. Natl. Acad. Sci.U.S.A., 82:3320-3324 (1985); a leaf-specific and light-induced promotersuch as that from cab or rubisco, Simpson et al., EMBO J.,4(11):2723-2729 (1985) and Timko et al., Nature, 318:579-582 (1985); ananther-specific promoter such as that from LAT52, Twell et al., Mol.Gen. Genetics, 217:240-245 (1989); a pollen-specific promoter such asthat from Zm13, Guerrero et al., Mol. Gen. Genetics, 244:161-168 (1993);or a microspore-preferred promoter such as that from apg, Twell et al.,Sex. Plant Reprod., 6:217-224 (1993).

Signal Sequences for Targeting Proteins to Subcellular Compartments

Transport of protein or peptide molecules produced by transgenes to asubcellular compartment such as a chloroplast, vacuole, peroxisome,glyoxysome, cell wall, or mitochondrion, or for secretion into anapoplast, is accomplished by operably linking a nucleotide sequenceencoding a signal sequence to the 5′ or 3′ end of a gene encoding theprotein or peptide of interest. Targeting sequences at the 5′ or 3′ endof the structural gene may determine, during protein synthesis andprocessing, where the encoded protein is ultimately compartmentalized.

Many signal sequences are known in the art. See, for example, Becker etal., Plant Mol. Biol., 20:49 (1992); Close, P. S., Master's Thesis, IowaState University (1993); Knox, C. et al., “Structure and Organization ofTwo Divergent Alpha-Amylase Genes from Barley,” Plant Mol. Biol., 9:3-17(1987); Lerner et al., Plant Physiol., 91:124-129 (1989); Fontes et al.,Plant Cell, 3:483-496 (1991); Matsuoka et al., Proc. Natl. Acad. Sci.,88:834 (1991); Gould et al., J. Cell. Biol., 108:1657 (1989); Creissenet al., Plant J., 2:129 (1991); Kalderon et al., “A short amino acidsequence able to specify nuclear location,” Cell, 39:499-509 (1984); andSteifel et al., “Expression of a maize cell wall hydroxyproline-richglycoprotein gene in early leaf and root vascular differentiation,”Plant Cell, 2:785-793 (1990).

Foreign Protein Genes and Agronomic Genes

Agronomically significant genes that may be transformed into rice plantsin accordance with the present invention include, for example, thefollowing:

1. Genes that Confer Resistance to Pests or Disease:

-   -   A. Plant disease resistance genes. Plant defenses are often        activated by specific interaction between the product of a        disease resistance gene (R) in the plant and the product of a        corresponding avirulence (Avr) gene in the pathogen. A plant may        be transformed with a cloned resistance gene to engineer plants        that are resistant to specific pathogen strains. See, e.g.,        Jones et al., Science 266:789 (1994) (cloning of the tomato Cf-9        gene for resistance to Cladosporium fulvum); Martin et al.,        Science 262:1432 (1993) (tomato Pto gene for resistance to        Pseudomonas syringae pv. Tomato encodes a protein kinase); and        Mindrinos et al., Cell 78:1089 (1994) (Arabidopsis RSP2 gene for        resistance to Pseudomonas syringae).    -   B. A Bacillus thuringiensis protein, a derivative thereof, or a        synthetic polypeptide modeled thereon. See, e.g., Geiser et al.,        Gene 48:109 (1986), disclosing the cloning and nucleotide        sequence of a Bt-endotoxin gene. DNA molecules encoding        endotoxin genes may be obtained from American Type Culture        Collection, Manassas, Va., e.g., under ATCC Accession Nos.        40098, 67136, 31995, and 31998.    -   C. A lectin. See, for example, Van Damme et al., Plant Molec.        Biol. 24:25 (1994), disclosing the nucleotide sequences of        several Clivia miniata mannose-binding lectin genes.    -   D. A vitamin-binding protein such as avidin. See PCT Application        US93/06487. This disclosure teaches the use of avidin and avidin        homologues as larvicides against insect pests.    -   E. An enzyme inhibitor, e.g., a protease or proteinase inhibitor        or an amylase inhibitor. See, e.g., Abe et al., J. Biol. Chem.        262:16793 (1987) (nucleotide sequence of rice cysteine        proteinase inhibitor); Huub et al., Plant Molec. Biol.        21:985 (1993) (nucleotide sequence of cDNA encoding tobacco        proteinase inhibitor 1); and Sumitani et al., Biosci. Biotech.        Biochem. 57:1243 (1993) (nucleotide sequence of Streptomyces        nitrosporeus-amylase inhibitor).    -   F. An insect-specific hormone or pheromone such as an        ecdysteroid and juvenile hormone, a variant thereof, a mimetic        based thereon, or an antagonist or agonist thereof. See, e.g.,        Hammock et al., Nature, 344:458 (1990), disclosing baculovirus        expression of cloned juvenile hormone esterase, an inactivator        of juvenile hormone.    -   G. An insect-specific peptide or neuropeptide that, upon        expression, disrupts the physiology of the affected pest. See,        e.g., Regan, J. Biol. Chem. 269:9 (1994) (expression cloning        yields DNA coding for insect diuretic hormone receptor); and        Pratt et al., Biochem. Biophys. Res. Comm., 163:1243 (1989) (an        allostatin in Diploptera puntata). See also U.S. Pat. No.        5,266,317 to Tomalski et al., disclosing genes encoding        insect-specific, paralytic neurotoxins.    -   H. An insect-specific venom produced in nature by a snake, a        wasp, etc. For example, see Pang et al., Gene, 116:165 (1992),        concerning heterologous expression in plants of a gene coding        for a scorpion insectotoxic peptide.    -   I. An enzyme responsible for hyperaccumulation of a monoterpene,        a sesquiterpene, a steroid, hydroxamic acid, a phenylpropanoid        derivative or another non-protein molecule with insecticidal        activity.    -   J. An enzyme involved in the modification, including        post-translational modification, of a biologically active        molecule; e.g., a glycolytic enzyme, a proteolytic enzyme, a        lipolytic enzyme, a nuclease, a cyclase, a transaminase, an        esterase, a hydrolase, a phosphatase, a kinase, a phosphorylase,        a polymerase, an elastase, a chitinase, or a glucanase, either        natural or synthetic. See PCT Application WO 9302197 to Scott et        al., which discloses the nucleotide sequence of a callase gene.        DNA molecules that contain chitinase-encoding sequences can be        obtained, for example, from the American Type Culture Collection        under Accession Nos. 39637 and 67152. See also Kramer et al.,        Insect Biochem. Molec. Biol. 23:691 (1993), which discloses the        nucleotide sequence of a cDNA encoding tobacco hookworm        chitinase; and Kawalleck et al., Plant Molec. Biol., 21:673        (1993), which discloses the nucleotide sequence of the parsley        ubi4-2 polyubiquitin gene.    -   K. A molecule that stimulates signal transduction. See, e.g.,        Botella et al., Plant Molec. Biol., 24:757 (1994), which        discloses nucleotide sequences for mung bean calmodulin cDNA        clones; and Griess et al., Plant Physiol., 104:1467 (1994),        which discloses the nucleotide sequence of a maize calmodulin        cDNA clone.    -   L. An antimicrobial or amphipathic peptide. See PCT Application        WO 9516776 (disclosing peptide derivatives of Tachyplesin that        inhibit fungal plant pathogens); and PCT Application WO 9518855        (disclosing synthetic antimicrobial peptides that confer disease        resistance).    -   M. A membrane permease, a channel former or a channel blocker.        See, e.g., Jaynes et al., Plant Sci., 89:43 (1993), which        discloses heterologous expression of a cecropin lytic peptide        analog to render transgenic tobacco plants resistant to        Pseudomonas solanacearum.    -   N. A viral-invasive protein or a complex toxin derived        therefrom. For example, the accumulation of viral coat proteins        in transformed plant cells induces resistance to viral infection        or disease development caused by the virus from which the coat        protein gene is derived, as well as by related viruses. Coat        protein-mediated resistance has been conferred upon transformed        plants against alfalfa mosaic virus, cucumber mosaic virus,        tobacco streak virus, potato virus X, potato virus Y, tobacco        etch virus, tobacco rattle virus, and tobacco mosaic virus. See        Beachy et al., Ann. Rev. Phytopathol., 28:451 (1990).    -   O. An insect-specific antibody or an immunotoxin derived        therefrom. Thus, an antibody targeted to a critical metabolic        function in the insect gut inactivates an affected enzyme,        killing the insect. See Taylor et al., Abstract #497, Seventh        Int'l Symposium on Molecular Plant-Microbe Interactions        (Edinburgh, Scotland, 1994) (enzymatic inactivation in        transgenic tobacco via production of single-chain antibody        fragments).    -   P. A virus-specific antibody. See, e.g., Tavladoraki et al.,        Nature, 366:469 (1993), showing protection of transgenic plants        expressing recombinant antibody genes from virus attack.    -   Q. A developmental-arrest protein produced in nature by a        pathogen or a parasite.

For example, fungal endo-1,4-D-polygalacturonases facilitate fungalcolonization and plant nutrient release by solubilizing plant cell wallhomo-1,4-D-galacturonase. See Lamb et al., Bio/Technology, 10:1436(1992). The cloning and characterization of a gene that encodes a beanendopolygalacturonase-inhibiting protein is described by Toubart et al.,Plant 1, 2:367 (1992).

-   -   R. A developmental-arrest protein produced in nature by a plant.        For example, Logemann et al., Bio/Technology, 10:305 (1992)        reported that transgenic plants expressing the barley        ribosome-inactivating gene have an increased resistance to        fungal disease.        2. Genes that Confer Additional Resistance to a Herbicide,        Beyond that which is Inherent in ‘CL261,’ for Example:    -   A. A herbicide that inhibits the growing point or meristem, such        as an imidazolinone or a sulfonylurea. Exemplary genes in this        category code for mutant ALS and AHAS enzymes as described, for        example, by Lee et al., EMBO J., 7:1241 (1988); and Miki et al.,        Theor. Appl. Genet., 80:449 (1990), respectively. See,        additionally, U.S. Pat. Nos. 5,545,822; 5,736,629; 5,773,703;        5,773,704; 5,952,553; 6,274,796; 6,943,280; 7,019,196;        7,345,221; 7,399,905; and Published International Patent        Applications WO 00/27182 and WO 01/85970. Resistance to        AHAS-acting herbicides may be through a mechanism other than a        resistant AHAS enzyme. See, e.g., U.S. Pat. No. 5,545,822.    -   B. Glyphosate. Resistance may be imparted by mutant        5-enolpyruvl-3-phosphikimate synthase (EPSP) and aroA genes.        Other phosphono compounds such as glufosinate. Resistance may be        imparted by phosphinothricin acetyl transferase, PAT and        Streptomyces hygroscopicus phosphinothricin-acetyl transferase,        bar, genes. Pyridinoxy or phenoxy propionic acids and        cyclohexones. Resistance may be imparted by ACCase        inhibitor-encoding genes. See, e.g., U.S. Pat. No. 4,940,835 to        Shah et al., which discloses the nucleotide sequence of a form        of EPSP that confers glyphosate resistance. A DNA molecule        encoding a mutant aroA gene can be obtained under ATCC Accession        Number 39256, and the nucleotide sequence of the mutant gene is        disclosed in U.S. Pat. No. 4,769,061 to Comai. European Patent        Application No. 0333033 to Kumada et al.; and U.S. Pat. No.        4,975,374 to Goodman et al., disclose nucleotide sequences of        glutamine synthetase genes that confer resistance to herbicides        such as L-phosphinothricin. The nucleotide sequence of a        phosphinothricin-acetyl-transferase gene is provided in European        Application No. 0242246 to Leemans et al. and DeGreef et al.,        Bio/Technology, 7:61 (1989), describing the production of        transgenic plants that express chimeric bar genes coding for        phosphinothricin acetyl transferase activity. Examples of genes        conferring resistance to phenoxy propionic acids and        cyclohexones, such as sethoxydim and haloxyfop, are the Accl-S1,        Accl-S2, and Accl-S3 genes described by Marshall et al., Theor.        Appl. Genet., 83:435 (1992).    -   C. A herbicide that inhibits photosynthesis, such as a triazine        (psbA and gs+ genes) or a benzonitrile (nitrilase gene).        Przibilla et al., Plant Cell, 3:169 (1991), describe the        transformation of Chlamydomonas with plasmids encoding mutant        psbA genes. Nucleotide sequences for nitrilase genes are        disclosed in U.S. Pat. No. 4,810,648 to Stalker, and DNA        molecules containing these genes are available under ATCC        Accession Nos. 53435, 67441, and 67442. Cloning and expression        of DNA coding for a glutathione S-transferase is described by        Hayes et al., Biochem. J., 285:173 (1992).        3. Genes that Confer or Contribute to a Value-added Trait, such        as:    -   A. Modified fatty acid metabolism, for example, by transforming        a plant with an antisense sequence to stearyl-ACP desaturase, to        increase stearic acid content of the plant. See Knultzon et al.,        Proc. Natl. Acad. Sci. U.S.A. 89:2624 (1992).    -   B. Decreased Phytate Content        -   1) Introduction of a phytase-encoding gene would enhance            breakdown of phytate, adding more free phosphate to the            transformed plant. See, e.g., Van Hartingsveldt et al.,            Gene, 127:87 (1993), which discloses the nucleotide sequence            of an Aspergillus niger phytase gene.        -   2) A gene may be introduced to reduce phytate content. For            example, this may be accomplished by cloning, and then            reintroducing DNA associated with an allele that is            responsible for maize mutants characterized by low levels of            phytic acid, or a homologous or analogous mutation in rice            may be used. See Raboy et al., Maydica, 35:383 (1990).    -   C. Carbohydrate composition may be modified, for example, by        transforming plants with a gene coding for an enzyme that alters        the branching pattern of starch. See Shiroza et al., J.        Bacteol., 170:810 (1988) (nucleotide sequence of Streptococcus        mutant fructosyltransferase gene); Steinmetz et al., Mol. Gen.        Genet., 20:220 (1985) (nucleotide sequence of Bacillus subtilis        levansucrase gene); Pen et al., Bio/Technology, 10:292 (1992)        (production of transgenic plants that express Bacillus        lichenifonnis amylase); Elliot et al., Plant Molec.

Biol., 21:515 (1993) (nucleotide sequences of tomato invertase genes);Søgaard et al., J. Biol. Chem., 268:22480 (1993) (site-directedmutagenesis of barley amylase gene); and Fisher et al., Plant Physiol.,102:1045 (1993) (maize endosperm starch branching enzyme 11).

Methods for Rice Transformation

Numerous methods for plant transformation are known in the art,including both biological and physical transformation protocols. See,e.g., Miki, et al., “Procedures for Introducing Foreign DNA into Plants”in Methods in Plant Molecular Biology and Biotechnology; Glick B. R. andThompson, J. E. (Eds.) (CRC Press, Inc., Boca Raton, 1993), pp. 67-88.In addition, expression vectors and in vitro culture methods for plantcell or tissue transformation and regeneration of plants are known inthe art. See, e.g., Gruber et al., “Vectors for Plant Transformation” inMethods in Plant Molecular Biology and Biotechnology, Glick B. R. andThompson, J. E. (Eds.) (CRC Press, Inc., Boca Raton, 1993), pp. 89-119.

A. Agrobacterium-Mediated Transformation

One method for introducing an expression vector into plants is based onthe natural transformation system of Agrobacterium. See, e.g., Horsch etal., Science, 227:1229 (1985). A. tumefaciens and A. rhizogenes areplant pathogenic soil bacteria that genetically transform plant cells.The Ti and Ri plasmids of A. tumefaciens and A. rhizogenes,respectively, carry genes responsible for genetic transformation ofplants. See, e.g., Kado, C. I., Crit. Rev. Plant Sci., 10:1 (1991).Descriptions of Agrobacterium vector systems and methods forAgrobacterium-mediated gene transfer are provided by Gruber et al.,supra; Miki et al., supra; and Moloney, et al., Plant Cell Reports,8:238 (1989). See also U.S. Pat. No. 5,591,616.

B. Direct Gene Transfer

Despite the fact the host range for Agrobacterium-mediatedtransformation is broad, it is more difficult to transform some cerealcrop species and gymnosperms via this mode of gene transfer, althoughsuccess has been achieved in both rice and corn. See Hiei et al., ThePlant Journal, 6:271-282 (1994); and U.S. Pat. No. 5,591,616. Othermethods of plant transformation exist as alternatives toAgrobacterium-mediated transformation.

A generally applicable method of plant transformation ismicroprojectile-mediated (so-called “gene gun”) transformation, in whichDNA is carried on the surface of microprojectiles, typically 1 to 4 μmin diameter. The expression vector is introduced into plant tissues witha biolistic device that accelerates the microprojectiles to typicalspeeds of 300 to 600 m/s, sufficient to penetrate plant cell walls andmembranes. Sanford et al., Part. Sci. Technol., 5:27 (1987); Sanford, J.C., Trends Biotech., 6:299 (1988); Klein et al., Bio/Technology,6:559-563 (1988); Sanford, J. C., Physiol Plant, 7:206 (1990); and Kleinet al., Biotechnology, 10:268 (1992). Various target tissues may bebombarded with DNA-coated microprojectiles to produce transgenic plants,including, for example, callus (Type I or Type II), immature embryos,and meristematic tissue.

Another method for physical delivery of DNA to plants is sonication oftarget cells. Zhang et al., Bio/Technology, 9:996 (1991). Alternatively,liposome or spheroplast fusion has been used to introduce expressionvectors into plants. Deshayes et al., EMBO J., 4:2731 (1985); andChristou et al., Proc Natl. Acad. Sci. U.S.A., 84:3962 (1987). Directuptake of DNA into protoplasts, using CaCl₂ precipitation, polyvinylalcohol or poly-L-ornithine, has also been reported. Hain et al., Mol.Gen. Genet., 199:161 (1985); and Draper et al., Plant Cell Physiol.,23:451 (1982). Electroporation of protoplasts and whole cells andtissues has also been described. Donn et al., in Abstracts of VIIthInternational Congress on Plant Cell and Tissue Culture IAPTC, A2-38, p.53 (1990); D'Halluin et al., Plant Cell, 4:1495-1505 (1992); and Spenceret al., Plant Mol. Biol., 24:51-61 (1994).

Following transformation of rice target tissues, expression of aselectable marker gene allows preferential selection of transformedcells, tissues, or plants, using regeneration and selection methodsknown in the art.

These methods of transformation may be used for producing a transgenicinbred line. The transgenic inbred line may then be crossed with anotherinbred line (itself either transformed or non-transformed), to produce anew transgenic inbred line. Alternatively, a genetic trait that has beenengineered into a particular rice line may be moved into another lineusing traditional crossing and backcrossing techniques. For example,backcrossing may be used to move an engineered trait from a public,non-elite inbred line into an elite inbred line, or from an inbred linecontaining a foreign gene in its genome into an inbred line or linesthat do not contain that gene.

The term “inbred rice plant” should be understood also to include singlegene conversions of an inbred line. Backcrossing methods can be usedwith the present invention to improve or introduce a characteristic intoan inbred line.

Many single gene traits have been identified that are not regularlyselected for in the development of a new inbred line, but that may beimproved by crossing and backcrossing. Single gene traits may or may notbe transgenic. Examples of such traits include male sterility, waxystarch, herbicide resistance, resistance for bacterial or fungal orviral disease, insect resistance, male fertility, enhanced nutritionalquality, yield stability, and yield enhancement. These genes aregenerally inherited through the nucleus. Known exceptions to the nucleargenes include some genes for male sterility that are inheritedcytoplasmically, but that still act functionally as single gene traits.Several single gene traits are described in U.S. Pat. Nos. 5,777,196;5,948,957; and 5,969,212.

DEPOSIT INFORMATION

A sample of the rice cultivar designated ‘CL261’ was deposited with theAmerican Type Culture Collection (ATCC), 10801 University Boulevard,Manassas, Va. 20110-2209 on Oct. 8, 2009, and was assigned ATCCAccession No. PTA-10388. This deposit was made under the BudapestTreaty.

MISCELLANEOUS

The complete disclosures of all references cited in this specificationare hereby incorporated by reference. In the event of an otherwiseirreconcilable conflict, however, the present specification shallcontrol.

1. A rice seed of the variety ‘CL261,’ wherein a representative sampleof said seed has been deposited under ATCC Accession No. PTA-10388.
 2. Aplant, or a part thereof, produced by growing the seed of claim
 1. 3. Amethod for producing rice plants, said method comprising planting aplurality of rice seeds as recited in claim 1 under conditions favorablefor the growth of rice plants.
 4. The method of claim 3, additionallycomprising the step of producing rice seed from the resulting riceplants.
 5. The rice seed produced by the method of claim
 4. 6. Themethod of claim 3, additionally comprising the step of applyingherbicide in the vicinity of the rice plants to control weeds, whereinthe herbicide normally inhibits acetohydroxyacid synthase, at levels ofthe herbicide that would normally inhibit the growth of a rice plant. 7.The method of claim 6, wherein the herbicide comprises a sulfonylurea.8. The method of claim 6, wherein the herbicide comprises animidazolinone.
 9. The method of claim 6, wherein the herbicide comprisesimazethapyr or imazamox.
 10. Pollen of the plant of claim
 2. 11. Anovule of the plant of claim
 2. 12. A rice plant, or a part thereof,having essentially all of the physiological and morphologicalcharacteristics of the rice plant of claim 2, including theimidazolinone herbicide resistance characteristics of ‘CL261.’
 13. Atissue culture of regenerable cells or protoplasts produced from therice plant of claim
 2. 14. The tissue culture of claim 13, wherein saidcells or protoplasts are produced from a tissue selected from the groupconsisting of embryos, meristematic cells, pollen, leaves, anthers,roots, root tips, flowers, seeds, and stems.
 15. A rice plantregenerated from the tissue culture of claim 14, said rice plant havingall or essentially all of the morphological and physiologicalcharacteristics of ‘CL261,’ including the imidazolinone herbicideresistance characteristics of ‘CL261.’
 16. A method for producing riceseed, said method comprising crossing a first parent rice plant with asecond parent rice plant, and harvesting the resulting hybrid rice seed,wherein the first parent rice plant or the second parent rice plant isthe rice plant of claim 2, wherein, if the hybrid rice seed is grown,then the rice plants grown from the hybrid rice seed will express theimidazolinone herbicide resistance characteristics of ‘CL261.’
 17. Ahybrid rice seed produced by the method of claim 16, wherein, if saidhybrid rice seed is grown, then the rice plants grown from said hybridrice seed will express the imidazolinone herbicide resistancecharacteristics of ‘CL261.’
 18. The method of claim 16, additionallycomprising the step of planting a plurality of the hybrid rice seedunder conditions favorable for the growth of rice plants.
 19. The methodof claim 18, additionally comprising the step of producing rice seedfrom the resulting rice plants; wherein, if the resulting rice seed isgrown, then at least some rice plants grown from the resulting rice seedwill express the imidazolinone herbicide resistance characteristics of‘CL261.’
 20. A plurality of rice seed produced by the method of claim19; wherein, if said resulting rice seed is grown, then at least somerice plants grown from said resulting rice seed will express theimidazolinone herbicide resistance characteristics of ‘CL261.’
 21. Themethod of claim 18, additionally comprising the step of applyingherbicide in the vicinity of the rice plants to control weeds, whereinthe herbicide normally inhibits acetohydroxyacid synthase, at levels ofthe herbicide that would normally inhibit the growth of a rice plant.22. The method of claim 21, wherein the herbicide comprises asulfonylurea.
 23. The method of claim 21, wherein the herbicidecomprises an imidazolinone.
 24. The method of claim 21, wherein theherbicide comprises imazethapyr or imazamox.
 25. A method of producing arice plant with enhanced herbicide resistance, said method comprisingtransforming the rice plant of claim 2 with a transgene that confersherbicide resistance, in addition to the herbicide resistance that isinherent in ‘CL261’ rice.
 26. A herbicide resistant rice plant or riceseed produced by the method of claim
 25. 27. A method of producing aninsect resistant rice plant, said method comprising transforming therice plant of claim 2 with a transgene that confers insect resistance.28. An insect resistant rice plant or rice seed produced by the methodof claim
 27. 29. A method of producing a disease resistant rice plant,said method comprising transforming the rice plant of claim 2 with atransgene that confers disease resistance.
 30. A disease resistant riceplant or rice seed produced by the method of claim
 29. 31. A method ofproducing a rice plant with modified fatty acid or modified carbohydratemetabolism, said method comprising transforming the rice plant of claim2 with at least one transgene encoding a protein selected from the groupconsisting of fructosyltransferase, levansucrase, alpha-amylase,invertase, and starch-branching enzyme; or encoding an antisensesequence to stearyl-ACP desaturase.
 32. A rice plant or rice seed havingmodified fatty acid or modified carbohydrate metabolism, wherein saidrice plant or rice seed is produced by the method of claim
 31. 33. Amethod of introducing a desired trait into rice cultivar ‘CL261,’ saidmethod comprising the steps of: (a) crossing plants as recited in claim2 with plants of another rice line expressing the desired trait, toproduce progeny plants; (b) selecting progeny plants that express thedesired trait, to produce selected progeny plants; (c) crossing theselected progeny plants with plants as recited in claim 2 to produce newprogeny plants; (d) selecting new progeny plants that express both thedesired trait and some or all of the physiological and morphologicalcharacteristics of rice cultivar ‘CL261,’ to produce new selectedprogeny plants; and (e) repeating steps (c) and (d) three or more timesin succession, to produce selected higher generation backcross progenyplants that express both the desired trait and essentially all of thephysiological and morphological characteristics of rice cultivar‘CL261,’ as described in the VARIETY DESCRIPTION INFORMATION of thespecification, determined at a 5% significance level, when grown in thesame environmental conditions; and wherein the selected plants expressthe imidazolinone herbicide resistance characteristics of ‘CL261.’
 34. Arice seed produced by the method of claim 33; wherein, if said rice seedis grown, then the rice plants grown from said rice seed will expressthe imidazolinone herbicide resistance characteristics of ‘CL261.’ 35.The method of claim 33, additionally comprising the step of planting aplurality of rice seed produced by selected higher generation backcrossprogeny plants under conditions favorable for the growth of rice plants.36. The method of claim 35, additionally comprising the step ofproducing rice seed from the resulting rice plants.
 37. The rice seedresulting from the method of claim 36; wherein, if said resulting riceseed is grown, then the rice plants grown from said resulting rice seedwill express the imidazolinone herbicide resistance characteristics of‘CL261.’
 38. The method of claim 35, additionally comprising the step ofapplying herbicide in the vicinity of the rice plants to control weeds,wherein the herbicide normally inhibits acetohydroxyacid synthase, atlevels of the herbicide that would normally inhibit the growth of a riceplant.
 39. The method of claim 38, wherein the herbicide comprises asulfonylurea.
 40. The method of claim 38, wherein the herbicidecomprises an imidazolinone.
 41. The method of claim 38, wherein theherbicide comprises imazethapyr or imazamox.
 42. The method of claim 33,wherein the desired trait is selected from the group consisting of malesterility; herbicide resistance; insect resistance; and resistance tobacterial, fungal, or viral disease.
 43. A method for producing hybridrice seed; said method comprising crossing a first parent rice plantwith a second parent rice plant, and harvesting the resulting hybridrice seed; wherein either the first parent rice plant, or the secondparent rice plant, but not both, is a rice plant of the variety ‘CL261’;wherein a representative sample of rice seed of the variety ‘CL261’ hasbeen deposited under ATCC Accession No. PTA-10388; and wherein, if thehybrid rice seed is grown, then the resulting hybrid rice plants willexpress the following characteristics: (a) the hybrid rice plantexpresses a mutant acetohydroxyacid synthase whose enzymatic activity isdirectly resistant to normally-inhibitory levels of aherbicidally-effective imidazolinone; (b) the hybrid rice plant isresistant to each of the following imidazolinone herbicides, at levelsof the imidazolinone herbicides that would normally inhibit the growthof a rice plant: imazethapyr, imazapic, imazaquin, imazamox, andimazapyr; (c) the hybrid rice plant is resistant to each of thefollowing sulfonylurea herbicides, at levels of the sulfonylureaherbicides that would normally inhibit the growth of a rice plant:nicosulfuron, metsulfuron methyl, thifensulfuron methyl, and tribenuronmethyl; and (d) the hybrid rice plant is sensitive to each of thefollowing sulfonylurea herbicides, at levels of the sulfonylureaherbicides that would normally inhibit the growth of a rice plant:sulfometuron methyl, chlorimuron ethyl, and rimsulfuron.
 44. Hybrid riceseed produced by the method of claim 43; wherein, if said hybrid riceseed is grown, then the resulting hybrid rice plants will express thefollowing characteristics: (a) the hybrid rice plant expresses a mutantacetohydroxyacid synthase whose enzymatic activity is directly resistantto normally-inhibitory levels of a herbicidally-effective imidazolinone;(b) the hybrid rice plant is resistant to each of the followingimidazolinone herbicides, at levels of the imidazolinone herbicides thatwould normally inhibit the growth of a rice plant: imazethapyr,imazapic, imazaquin, imazamox, and imazapyr; (c) the hybrid rice plantis resistant to each of the following sulfonylurea herbicides, at levelsof the sulfonylurea herbicides that would normally inhibit the growth ofa rice plant: nicosulfuron, metsulfuron methyl, thifensulfuron methyl,and tribenuron methyl; and (d) the hybrid rice plant is sensitive toeach of the following sulfonylurea herbicides, at levels of thesulfonylurea herbicides that would normally inhibit the growth of a riceplant: sulfometuron methyl, chlorimuron ethyl, and rimsulfuron.
 45. Ahybrid rice plant, or a part thereof, produced by growing the hybridrice seed of claim
 44. 46. A method for producing rice plants, saidmethod comprising planting a plurality of hybrid rice seeds as recitedin claim 44 under conditions favorable for the growth of rice plants.47. A method as recited in claim 46, additionally comprising the step ofharvesting rice seed produced by the resulting hybrid rice plants. 48.The rice seed harvested by the method of claim
 47. 49. A method asrecited in claim 46, additionally comprising the step of applyingherbicide in the vicinity of the rice plants to control weeds, whereinthe herbicide normally inhibits acetohydroxyacid synthase, at levels ofthe herbicide that would normally inhibit the growth of a rice plant.50. A method as recited in claim 49, wherein the herbicide comprises aherbicidally effective sulfonylurea.
 51. A method as recited in claim49, wherein the herbicide comprises a herbicidally effectiveimidazolinone.
 52. A method as recited in claim 49, wherein theherbicide comprises imazethapyr or imazamox.
 53. A method as recited inclaim 44, wherein either the first parent or the second parent ismale-sterile.
 54. A method of producing a rice plant with enhancedherbicide resistance; said method comprising transforming a rice plantof the variety ‘CL261’ with a transgene that confers herbicideresistance, in addition to the herbicide resistance that is inherent in‘CL261’ rice; wherein a representative sample of rice seed of thevariety ‘CL261’ has been deposited under ATCC Accession No. PTA-10388;and wherein the transformed rice plants express the followingcharacteristics: (a) the rice plant expresses a mutant acetohydroxyacidsynthase whose enzymatic activity is directly resistant tonormally-inhibitory levels of a herbicidally-effective imidazolinone;(b) the rice plant is resistant to each of the following imidazolinoneherbicides, at levels of the imidazolinone herbicides that wouldnormally inhibit the growth of a rice plant: imazethapyr, imazapic,imazaquin, imazamox, and imazapyr; (c) the rice plant is resistant toeach of the following sulfonylurea herbicides, at levels of thesulfonylurea herbicides that would normally inhibit the growth of a riceplant: nicosulfuron, metsulfuron methyl, thifensulfuron methyl, andtribenuron methyl; and (d) the rice plant is sensitive to each of thefollowing sulfonylurea herbicides, at levels of the sulfonylureaherbicides that would normally inhibit the growth of a rice plant:sulfometuron methyl, chlorimuron ethyl, and rimsulfuron.
 55. A herbicideresistant rice plant or rice seed produced by the method of claim 54,wherein the transformed rice plants or the rice plants grown from thetransformed rice seed will express the following characteristics: (a)the rice plant expresses a mutant acetohydroxyacid synthase whoseenzymatic activity is directly resistant to normally-inhibitory levelsof a herbicidally-effective imidazolinone; (b) the rice plant isresistant to each of the following imidazolinone herbicides, at levelsof the imidazolinone herbicides that would normally inhibit the growthof a rice plant: imazethapyr, imazapic, imazaquin, imazamox, andimazapyr; (c) the rice plant is resistant to each of the followingsulfonylurea herbicides, at levels of the sulfonylurea herbicides thatwould normally inhibit the growth of a rice plant: nicosulfuron,metsulfuron methyl, thifensulfuron methyl, and tribenuron methyl; and(d) the rice plant is sensitive to each of the following sulfonylureaherbicides, at levels of the sulfonylurea herbicides that would normallyinhibit the growth of a rice plant: sulfometuron methyl, chlorimuronethyl, and rimsulfuron.
 56. A method of producing an insect resistantrice plant, said method comprising transforming a rice plant of thevariety ‘CL261’ with a transgene that confers insect resistance; whereina representative sample of rice seed of the variety ‘CL261’ has beendeposited under ATCC Accession No. PTA-10388.
 57. An insect resistantrice plant or rice seed produced by the method of claim
 56. 58. A methodof producing a disease resistant rice plant, said method comprisingtransforming a rice plant of the variety ‘CL261’ with a transgene thatconfers disease resistance; wherein a representative sample of rice seedof the variety ‘CL261’ has been deposited under ATCC Accession No.PTA-10388.
 59. A disease resistant rice plant or rice seed produced bythe method of claim
 58. 60. A method of producing a rice plant withmodified fatty acid or carbohydrate metabolism, said method comprisingtransforming a rice plant of the variety ‘CL261’ with at least onetransgene encoding a protein selected from the group consisting offructosyltransferase, levansucrase, alpha-amylase, invertase, andstarch-branching enzyme; or encoding an antisense sequence tostearyl-ACP desaturase; wherein a representative sample of rice seed ofthe variety ‘CL261’ has been deposited under ATCC Accession No.PTA-10388.
 61. A rice plant or rice seed having modified fatty acid orcarbohydrate metabolism, wherein said rice plant or rice seed isproduced by the method of claim
 60. 62. A method of introducing adesired trait into rice cultivar ‘CL261’, said method comprising thesteps of: (a) crossing rice cultivar ‘CL261’ with plants of another riceline expressing the desired trait, to produce progeny plants; wherein arepresentative sample of rice seed of the variety ‘CL261’ has beendeposited under ATCC Accession No. PTA-10388; (b) selecting progenyplants that express the desired trait, to produce selected progenyplants; (c) crossing the selected progeny plants with ‘CL261’ plants toproduce new progeny plants; (d) selecting new progeny plants thatexpress both the desired trait and some or all of the physiological andmorphological characteristics of rice cultivar ‘CL261,’ to produce newselected progeny plants; and (e) repeating steps (c) and (d) three ormore times in succession, to produce selected higher generationbackcross progeny plants that express both the desired trait andessentially all of the physiological and morphological characteristicsof rice cultivar ‘CL261,’ as described in the VARIETY DESCRIPTIONINFORMATION of the specification, determined at a 5% significance level,when grown in the same environmental conditions; (f) the selected highergeneration backcross progeny plants express a mutant acetohydroxyacidsynthase whose enzymatic activity is directly resistant tonormally-inhibitory levels of a herbicidally-effective imidazolinone;(g) the selected higher generation backcross progeny plant is resistantto each of the following imidazolinone herbicides, at levels of theimidazolinone herbicides that would normally inhibit the growth of arice plant: imazethapyr, imazapic, imazaquin, imazamox, and imazapyr;(h) the selected higher generation backcross progeny plant is resistantto each of the following sulfonylurea herbicides, at levels of thesulfonylurea herbicides that would normally inhibit the growth of a riceplant: nicosulfuron, metsulfuron methyl, thifensulfuron methyl, andtribenuron methyl; and (i) the selected higher generation backcrossprogeny plant is sensitive to each of the following sulfonylureaherbicides, at levels of the sulfonylurea herbicides that would normallyinhibit the growth of a rice plant: sulfometuron methyl, chlorimuronethyl, and rimsulfuron.
 63. Rice seed harvested from selected highergeneration backcross progeny plants produced by the method of claim 62;wherein, if said rice seed is grown, then the resulting hybrid riceplants will express the following characteristics: (a) the rice plantexpresses a mutant acetohydroxyacid synthase whose enzymatic activity isdirectly resistant to normally-inhibitory levels of aherbicidally-effective imidazolinone; (b) the rice plant is resistant toeach of the following imidazolinone herbicides, at levels of theimidazolinone herbicides that would normally inhibit the growth of arice plant: imazethapyr, imazapic, imazaquin, imazamox, and imazapyr;(c) the rice plant is resistant to each of the following sulfonylureaherbicides, at levels of the sulfonylurea herbicides that would normallyinhibit the growth of a rice plant: nicosulfuron, metsulfuron methyl,thifensulfuron methyl, and tribenuron methyl; and (d) the rice plant issensitive to each of the following sulfonylurea herbicides, at levels ofthe sulfonylurea herbicides that would normally inhibit the growth of arice plant: sulfometuron methyl, chlorimuron ethyl, and rimsulfuron. 64.The method of claim 62, additionally comprising the step of planting,under conditions favorable for the growth of rice plants, a plurality ofrice seed harvested from selected higher generation backcross progenyplants.
 65. A method as recited in claim 64, additionally comprising thestep of harvesting rice seed produced by the resulting rice plants. 66.The rice seed harvested by the method of claim
 65. 67. A method asrecited in claim 64, additionally comprising the step of applyingherbicide in the vicinity of the rice plants to control weeds, whereinthe herbicide normally inhibits acetohydroxyacid synthase, at levels ofthe herbicide that would normally inhibit the growth of a rice plant.68. A method as recited in claim 67, wherein the herbicide comprises aherbicidally effective sulfonylurea.
 69. A method as recited in claim67, wherein the herbicide comprises a herbicidally effectiveimidazolinone.
 70. A method as recited in claim 67, wherein theherbicide comprises imazethapyr or imazamox.
 71. The method of claim 62,wherein the desired trait is selected from the group consisting of malesterility; herbicide resistance; insect resistance; and resistance tobacterial, fungal, or viral disease.
 72. A method for controlling weedsin the vicinity of rice, comprising contacting the rice with aherbicide, wherein said rice belongs to any of (a) variety ‘CL261’ or(b) a hybrid, derivative, or progeny of ‘CL261’ that expresses theimidazolinone herbicide resistance characteristics of ‘CL261.’
 73. Themethod according to claim 72, wherein the herbicide is an imidazolinoneherbicide, a sulfonylurea herbicide, or a combination thereof.
 74. Themethod according to claim 72, wherein the rice is a rice plant and saidcontacting comprises applying the herbicide in the vicinity of the riceplant.
 75. The method according to claim 74, wherein the herbicide isapplied to weeds in the vicinity of the rice plant.
 76. The methodaccording to claim 72, wherein the rice is a rice seed and saidcontacting comprises applying the herbicide to the rice seed.
 77. Amethod for treating rice, comprising contacting the rice with anagronomically acceptable composition, wherein said rice belongs to anyof (a) variety ‘CL261’ or (b) a hybrid, derivative, or progeny of‘CL261’ that expresses the imidazolinone herbicide resistancecharacteristics of ‘CL261.’
 78. The method according to claim 77,wherein the agronomically acceptable composition comprises at least oneagronomically acceptable active ingredient.
 79. The method according toclaim 78, wherein the agronomically acceptable active ingredient isselected from the group consisting of fungicides, insecticides,antibiotics, stress tolerance-enhancing compounds, growth promoters,herbicides, molluscicides, rodenticides, and animal repellants, andcombinations thereof.